Exhaust Riser or Elbow?

[KeelsonGraham]

Hi all,

Sorry, another newbie type question. Is what Catalina Direct calls an 'exhaust riser' the equivalent of an 'exhaust elbow'?

[WBev]

Yes.

[KeelsonGraham]

Thank you! Just one more question. Is the riser just as susceptible to becoming clogged over time as a conventional elbow?

[Noah]

Corroding and leaking are the usually symptoms more than clogging.

[KWKloeber]

Sorry, another newbie type question. Is what Catalina Direct calls an 'exhaust riser' the equivalent of an 'exhaust elbow'?

@Keel

Don't be sorry!!

Folks use different terms for different  "things."  Over time terms get conflated and become accepted, even if they don't hold their original meaning. IMO that's very unfortunate when it comes to boats. There's a heritage we should maintain.
For instance, folks call the cockpit sail locker a port lazarette.  A lazarette historically has a specific location on a boat.

An exhaust elbow typically simply turns downward, oftentimes but not always at a 45.  It's often used on stinkboats because (hopefully) they don't bury a rail so there's little chance of backflow thru the exhaust valves to the cylinders. 

A riser does what the term implies.

Google "westerbeke exhaust elbow" and "westerbeke exhaust riser"


. 

[KeelsonGraham]

Thanks guys.

I'm building a short-list of all the prime suspects for my (still) ongoing engine overheating issue.🙄

I'll start by replacing the thermostat, then re-furb the pump (again) then over winter I'll have the HX out and de-scale it. Sounds like the riser will now be last on my list of things to check/replace because there are no obvious leaks from it.

[KeelsonGraham]

Google "westerbeke exhaust elbow" and "westerbeke exhaust riser"

[/quote]

Dang, I wish I hadn't done that. Now I'm confused again!

[KeelsonGraham]

Looks completely different from CD's 'riser'

[Stu Jackson]

Looks completely different from CD's 'riser'

KG,

That's because it is.  And that is also why what we have on our boats is called a riser, and not an elbow.  Yanmars have elbows.  Universals on our boats have risers.  Yeah, westerbeke makes both but we don't have westerbekes.

Elbows get clogged because they have small apertures inside the elbow where the water turns 180 degrees.

Risers rarely get clogged, indeed in my 25 years I've never heard of a clogged riser.  Why?  Because it's just two big pipes coming together.  Where they fail is at the nipple where the hot gas and water meet; the weld fails or one pipe fails usually there.

[KeelsonGraham]

Thank you Stu, that makes sense. Just to be clear, the nipple your talking about is this thing circled in red?

I assume this small diameter pipe is where raw water gets injected into the exhaust?

[Jon W]

Correct.

It is rare, but possible for that small diameter "nipple" to get clogged from debris exiting the HX. Easy way to check is remove the hose from the nipple and poke something through it.

[Ron Hill]

Keel : It is possible but UNUSUAL to have that nipple clogged!!

A thought

[KWKloeber]

Looks completely different from CD's 'riser'

Now I'm confused again!

@Keelson

If you Google "Boats" or "Boats that use Universal engines" you'll see many different pictures of many different boats.  Some use similar parts, many are unique to the brand.  Boat and also component (like boat engine) manufacturers are worse at using different parts than auto manufacturers.  Note that the Universal riser is water-cooled (CD's is not cooled) and supplied by Westerbeke and that particular model did not exist in Universal Medalist Oskosh's world when it supplied the original Universals ("non-B series" engines) to CTY -- however Universal had a similar one (see photo 1.)

But Frank was frugal, to say the least, and fabricated (or had fabricated) components when CTY or a supplier could make something more economically than OEM!!  Like fabricating the engine panel and engine harness extension rather than buying Universal Medalist's ones -- or more-recently the Universal(/Westerbeke) made versions. 



The injection point you circled in red (some call it an injection tee or elbow, but the hose nipple is actually a Wye fitting) can be a source of overheating, "depending".   If it gets blocked with salt water gunk it can cause overheating (but it will reduce (so you can troubleshoot) the water flow out the exhaust.)  It's not normally an issue in fresh water. 
What temp TStat are you running? too high and it could deposit gunk there.

A minor point perhaps, but the picture you posted does not accurately reflect our exhaust.  The water injection to the muffler originates, not at the Exhaust Manifold (as pictured,) but at the HX.  I am 99-44/100% sure that the sketch reflects a seawater-cooled Atomic-4 gas burner or M-15 diesel, not our freshwater-cooled diesels.

Is the riser just as susceptible to becoming clogged over time as a conventional elbow?

An elbow is *TYPICALLY* not very susceptible because it's just a 45 bend in a pipe.  A 90 elbow is more susceptible than a 45, but again not that much.

Some risers are more susceptible than others - depending on the TYPE of riser.  As Stu explained the 1-5/8" pipe risers are not very susceptible to failure due to clogs because there are no major restrictions -- only elbows (or pipe sweep bends in the newer stainless ones.)

Types like the Westerbeke water-cooled (there are other brands) can be susceptible, again "depending" (.e.g, whether it's in salt or fresh, poor combustion, exhaust temperature.)

Pic 2 is another brand that was well-clogged, eh? (likely ZERO maintenance over its lifetime!)

In deference to Stu's knowledgebase about the C34, I do know that at least one C-34 that has the Westerbele water-cooled riser.
Go to the TechWiki site > Engines > Exhaust Systems > 1st article by Bill Shreeves.

I'll start by replacing the thermostat, then re-furb the pump (again) then over winter I'll have the HX out and de-scale it. Sounds like the riser will now be last on my list of things to check/replace because there are no obvious leaks from it.

Yes, that's one way of doing it. 
Playing Whack a Mole with replacing parts instead of troubleshooting to determine the cause. 

Let's try this.
Now let's try that. 
Then let's try something else.

And then ever sure in the end whether the root cause was found/corrected or if there are lurking contributing causes and one has simply fixed enough to "get by" for a while (until another cause worsens.)  On boats where out of sight is out of mind, there can be multiple contributing causes -- and (IMO) that's more typical than not.

Why not troubleshoot the causes, then fix/replace?

(BTW, a leak in a riser is not a symptom of one that might be contributing to overheating (it is a symptom of one that can kill you from carbon monoxide.)  The injection wye would be ONE of the easiest possible causes and higher on the list to investigate -- but not for me as it has never seen a drop of salt water.)

Replacing a TStat is good insurance but at least troubleshoot to determine if it was a cause contributing to the symptom.

Is she overheating or is the temp gauge reading high??  The symptoms?

Understand completely how your engine and exhaust works before throwing parts at it!!!

[KeelsonGraham]

Hi KW, thank you for that. The symptoms are excessive steam in exhaust and temp rising above 180 in anything above 1600 RPM. Runs fine at 1500 RPM. Apart from high temp, the engine starts immediately andruns as sweet as a nut. Water is coming from exhaust but I just have a feeling (from running other boats) that not enough may be coming out. Calorifier works fine. No excessive smoke in exhaust.

My strategy isn't so much whack a mole but to go systematically through everything. I've already done some things thanks to previous advice in another thread. Now I'm going to do it all again in this order:

1. Check accuracy of temp gage.
2. Check correct operation of thermostat
3. Replenish coolant and burp system (Done once)
4. Check raw water inlet for blockage (done once)
5. Check strainer for blockage (done twice)
6. Replace impeller and check housing (done once)
7. Clean HX (anode debris removed but I'm now going to de-scale it with Lime-Away)
8. Check injection nipple in riser for blockage.

Not on my list, so far either because I don't know how to do it or am going to wait until the end of the season, are:

1. Check operation of freshwater coolant pump.
2. Check operation of aqualift
2. Inspect riser for internal blockage

The only thing that's niggling me is the state of the impeller housing. In a previous thread I read that there must be no scoring and that it must be 'flat, flat, flat'. I didn't think mine was too bad, but now I'm not so sure.

[KWKloeber]

Overheating is NOT due to your freshwater cooling pump, muffler, or riser pipe.

The

• Coolant pump fails by a bad bearing and squeals and has play in the pulley/shaft (but it still pumps.)
• Riser, if blocked, will cause the Engine to not run smoothly (excessive backpressure.)
• Aqualift doesn't cool the engine (if it's blocked same as above.)
• Aqualift has nothing to check -- either it's exhausting gas/water -- or it is leaking at a seam (but still works.)